Basically, an Airdrop to us is a boxed of supplies that is being dropped off from a passing aircraft. There's actually no difference from the Airdrop that we can picture out to the Airdrop in cryptocurrencies, they just both means to drop something essential to us.
Airdrop in crypto is a distribution of token of the major token holders by requiring some simple tasks that are mainly doable virtually anywhere on the internet.
Sometimes, actually most of the times, when you thought of joining one you'll probably be wondering first whether is it a scam or is it legit, why do they give it for free? Just a quite direct answer to feed your curiosity, if you'll think of it thoroughly, it's actually one of their way to show how great the value of their tokens are and to increase engagement amongst its marketplace because of that the token will significantly increase its value as it scarce and gain more investors.
It depends. This is where common sense comes in. There are times that you'll fall to a scam Airdrops and completely lose all your effort for nothing, and sometimes as well it's passively quite profitable one. It's all up to you, there's nothing much to lose but there's something to win. You just have to try it yourself then you'll eventually know if it is scam soon enough if you pay attention to its composition.
As I mentioned, mostly, there are several tasks that you needed to complete first for you receive these tokens or it's very own platform currency where you can then exchange when you met the required threshold for withdrawal. These tasks include signing up as an official member by completing kyc where you will then link you cryptocurrency virtual wallet adresses (BCH, BTC, ETH, etc.), subscribing and following its social media accounts (usually on Twitter or Telegram), answering surveys, bringing more people to the platform, visiting its sponsor advertisement and watching videos, and many to mention. They will then reward you based on the tasks that you have completed.